1. Field of the Invention
The present invention relates to apparatus and methods for inspection or review of semiconductor wafers and masks.
2. Description of the Background Art
An electron beam (e-beam) apparatus based on a low-energy electron microscope (LEEM) configuration utilizes electrons reflecting of the surface of a flat substrate. Electron optical imaging systems for a LEEM configuration is complicated when compared to conventional straight-axis electron beam systems. The complication arises because the electron beam passes twice through one or more electron lenses. A design including a plurality of lenses arranged along one straight axis is therefore not practically feasible, and a beam separator is needed to split the incoming and outgoing beams.